Distillers grains are a viable feed option for dairy producers. However, field responses to feeding distillers have often included a reduction in milk fat.
“If we can identify ways to increase the inclusion rate of distillers without those negative effects of milk fat depression, we’re going to be able to increase ration formulation possibilities,” says Jackie Ploetz, a graduate student at Michigan State University, and formerly at the University of Illinois.
In a trial she did at the University of Illinois, Ploetz examined the effect of two different types of TMR mixers on the physical form and utilization of diets containing increasing amounts of modified wet distillers grains with solubles. She compared a horizontal paddle mixer with stationary knives to a vertical auger mixer and fed the distillers at inclusion rates of 10, 20, or 30 percent of ration dry matter.
Ploetz found no statistical difference in milk production between the two mixer treatments. However, there was an effect of mixer type on feed intake, with cows being fed with the paddle mixer having lower dry matter intake, she said at the 2012 Tri-State Dairy Nutrition Conference. There was a linear effect of distillers by mixer on milk fat yield and percent.
“When we increased the level of distillers, those cows being fed with the vertical mixer decreased (milk fat yield and percentage) at a greater rate,” Ploetz said.
For instance, when cows were fed 30 percent distillers grains with a paddle mixer, there was a 5 percent reduction in milk fat compared to cows fed 10 percent distillers with the same mixer. However, when cows were fed 30 percent distillers with a vertical mixer, there was a 20 percent reduction in milk fat compared to cows fed 10 percent distillers with the same mixer.
Those cows fed with a vertical mixer also had decreased feed conversion efficiency. “There also was a linear effect of distillers, so as we increased distillers we decreased feed conversion efficiency,” Ploetz said.